How the payment is calculated
An EMI, or equated monthly instalment, is a fixed payment that covers both interest and principal so that the loan is fully repaid by the end of the term. The formula distributes the total cost evenly across every month, which is why your payment stays the same even though the split between interest and principal shifts constantly.
That shifting split is the part borrowers most often find surprising. In the early years, the overwhelming majority of each payment goes to interest, because interest is charged on the outstanding balance and that balance is at its highest. Only later does the principal portion dominate. On a twenty year loan, you may be several years in before the two are even close to equal, which the schedule below the calculator makes visible.
What the term does to total cost
Extending the term reduces the monthly payment, which is why longer terms are attractive when affordability is tight. The trade-off is severe. A longer term means the balance stays high for longer, and interest accrues on that balance every month. Moving a mortgage from twenty years to thirty might reduce the payment by fifteen percent while increasing the total interest paid by well over half.
Running the calculation at several different terms before committing is worth the few minutes. The monthly figure is what lenders emphasise; the total repaid is what actually leaves your account.
The effect of the rate
Small differences in rate compound into large differences in cost over a long term. On a substantial loan over twenty years, half a percentage point can amount to a meaningful fraction of the original principal. This is why shopping between lenders, and negotiating, repays the effort considerably more than most people expect.
Prepayment
Because interest is charged on the outstanding balance, any extra payment made early reduces the balance for every subsequent month and therefore saves compounding interest. Overpayments made in the first few years of a long loan have a disproportionate effect. Before overpaying, check whether your agreement carries prepayment penalties, which are common on fixed-rate products.
What this calculator does not include
The figures here cover principal and interest only. Real borrowing costs usually include arrangement or processing fees, and for mortgages also property insurance, taxes and sometimes mortgage insurance. Those can add materially to the true monthly outgoing. The calculation also assumes a fixed rate throughout; on a variable rate product, payments will move with the underlying rate.
This tool provides general estimates for information only and is not financial advice. Figures from a lender will be authoritative, and a qualified financial adviser can assess your particular circumstances.
Frequently Asked Questions
What does EMI stand for?
Equated monthly instalment — a fixed monthly payment covering both interest and principal, sized so the loan is fully repaid by the end of the term.
Why is most of my early payment going to interest?
Interest is charged on the outstanding balance, which is at its highest at the start. As the balance falls, the interest portion shrinks and the principal portion grows.
Does a longer term save money?
It lowers the monthly payment but increases total interest substantially, because the balance stays high for longer. Always compare total repaid, not just the monthly figure.
Should I make extra payments?
Overpayments reduce the balance and therefore all future interest, with the biggest effect early in the term. Check first whether your agreement carries prepayment penalties.
Are fees and insurance included?
No. This calculates principal and interest only. Processing fees, property taxes and insurance are additional and can be significant.